v. 1a. To break or destroy or to be destroyed by explosion. He blew up the plane by means of a concealed bomb. The fireworks factory blew up when something went wrong in an electric switch. 1b. informal To explode with anger or strong feeling; lose control of yourself. When Father bent the nail for the third time, he blew up.
Compare: BLOW A FUSE. 1c. To stop playing well in a game or contest, usually because you are in danger of losing or are tired; especially : To lose skill or control in pitching baseball. The champion blew up and lost the tennis match. Our team was behind but the pitcher on the other team blew up and we got the winning runs. 2. informal To be ruined as if by explosion; be ended suddenly. The whole scheme for a big party suddenly blew up. 3a. To pump full of air; inflate. He blew his tires up at a filling station. 3b. To make (something) seem bigger or important. It was a small thing to happen but the newspapers had blown it up until it seemed important. 4. To bring on bad weather; also, to come on as bad weather. The wind had blown up a storm. A storm had blown up. 5. To copy in bigger form; enlarge. He blew up the snapshot to a larger size.